Emergency Medicine

Tox i c o l o g y 17 3

SPECIFIC POISONS

(iii) 300–500 mg/kg: severe toxicity with hyperthermia, marked

dehydration, agitation, confusion and an altered level of

consciousness, which may lead to coma.

(iv) More than 500 mg/kg ingested is associated with pulmonary and

cerebral oedema and may be fatal.

2 Gain i.v. access and send bloods for U&Es, blood sugar and a salicylate level.
(i) Perform arterial blood gases (ABGs) to detect respiratory
alkalosis or a metabolic acidosis in symptomatic patients.

MANAGEMENT

1 C a l l a n a i r way-sk i l led doc tor i m med iately to pa s s a c u f fed endot r ache a l t ube
if the patient is obtunded, unconscious or unable to protect their airway.

2 Commence a normal saline infusion to replace insensible losses associated
with hyperthermia, hyperventilation and vomiting.

3 Administer charcoal as soon as possible, even in patients with a delayed
presentation, as salicylates cause delayed gastric emptying. Consider repeat-
dose activated charcoal every 4 h to reduce salicylate absorption in the
following situations:
(i) Overdose of sustained-release aspirin.
(ii) Evidence of continued absorption with rising serum salicylate
levels.

4 Urinary alkalinization may reduce salicylate elimination from 20 to 5 h.
Consider in patients with signs and symptoms of salicylate toxicity, or a
serum sa licylate level of >300 mg/L (2.2 mmol/L).
(i) Give a bolus of 8.4% sodium bicarbonate 1 mmol/kg (1 mL/kg)
i.v.
(ii) Follow with an infusion of 8.4% sodium bicarbonate 100 mmol
(100 mL) in 5% dextrose solution 1 L, at a rate of 100–250 mL/h.
(iii) Titrate this bicarbonate infusion to maintain urinary pH >7.5
and urine output >1 mL/kg per h.

5 Monitor serum electrolytes, salicylate level and urinary pH every 2–4 h.
(i) Salicylate level:
(a) symptoms occur at 300 mg/L (2.2 mmol/L)
(b) significant toxicity occurs at 500 mg/L (3.6 mmol/L)
(c) repeat the level at least once. Rising levels indicate continued
drug absorption.
(ii) Potassium: significant hypokalaemia hinders salicylate
elimination so potassium may need to be replaced.

6 Patients with no clinical evidence of salicylate toxicity, normal ABGs and
falling serum salicylate levels 4 h apart may be medically cleared, ready for
psychiatric review.